Amalgam conveyor



Nov. 19, 1968 R. P1 SPINELLO AMALGAM CONVEYOR Filed Feb. 14, 1966 l INVENTOR. foy/940 P P//yfao United States Patent O 3,411,213 AMALGAMCQNVEYOR Ronald P. spinello, Westbury, NX., assignor to The DentistsSupply Company of New York, York, Pa., a corporation of New YorkContinuation-impart of application Ser. No. 437,806,

Mar. 8, 1965. This application Feb. 14, 1966, Ser.

Claims. (Cl. .S2-60) ABSTRACT 0F THE DISCLOSURE An amalgam condenser andcarrier operable to receive the ingredients to form dental amalgam andcomprising a housing in which at least the interior decreasesprogressively in diameter from adjacent an inlet opening to a dischargeopening adjacent the opposite end thereof, a screw conveyorcomplementary to and rotatable within the interior of said housing, saidconveyor having threads thereon of a uniform pitch and depth to define agroove comprising a spiral passage for amalgam which is of uniform depthand decreasing uniformly in diameter to the discharge opening of thehousing whereby, upon rotation of the screw in a feeding direction,amalgam simultaneously is fed to the discharge opening and is condensedwithout sharp changes in magnitude and direction to insure uninterruptedfeeding Imovement of the amalgam through said housing from said inlet tosaid discharge openings, thereby obviating any appreciable condensing ofamalgam after being discharged into a prepared dental cavity.

This application is a continuation-in-part of application Ser. No.437,806, filed Mar. 8, 1965 and now abandoned.

This invention relates in general to a dental tool and more particularlyto a conveyor for carrying amalgam from a reservoir directly to a toothto provide a desired filling, The design of this amalgam conveyor issuch that a degree of condensation is provided by the conveyor withoutcausing the amalgam to harden (set) prior to its being deposited in atooth cavity.

In lling cavities in teeth, dentists have had to use in general twoseparate tools; an amalgam carrier to pick up the amalgam, carry it tothe tooth and deposit it in the cavity, and an amalgam condenser tocondense or compact the plastic mass of amalgam in the cavity. Thedentist, or his assistant, mixes a quantity of amalgam, (primarilymercury and silver) usually of a suicient amount to accomplish onecomplete filling. The dentist picks up a small quantity of amalgam inthe amalgam carrier, carries it to the cavity and deposits it therein.The dentist next picks up an amalgam condenser in order to condense theplastic mass of amalgam in the cavity. The dentist then picks up anothersmall quantity of amalgam in the amalgam carrier, carries it to thetooth and deposits it in like manner followed by another condensingoperation. The filling of a tooth cavity may require many such trips foreach instrument, a time consuming procedure.

Since the amalgam solidies to a preliminary set state in a relativelyshort time, considerable speed is necessary for the filling operation.The prepared quantity of amalgam must be repeatedly manipulated ormulled to prevent this preliminary set. Furthermore, the dentalinstruments V f' 3,411,213 Patented Nov. 19, 1968 must be repeatedly setaside thereby running the risk of picking up foreign matter or bacteria.

The aim in the condensation of amalgam is to pack the amalgam crystals(mainly and usually silver) closely together so that the minimum amountof mercury is necessary for cohesion, the excess mercury being pressedout of the mix by the condensing procedure. The known and commonly usedtechniques of tamping for accomplishing this procedure all involvepushing into the amalgam mass with a suitably sized instrument. Thistamping is done with a reciprocating stroke action, either by hand or bymeans of a mechanical or electronic vibrating device. In thesetechniques, the action of carrying and the action of condensing are twoseparate procedures as described above.

It is an object of this invention to provide a new and useful means ofcondensing dental amalgam.

It has been found by applicant that if amalgam is fed into a cavityunder pressure and in a continuous way that the amalgam becomesprecondensed and is applied to the cavity in a condensed form. Thepressure that is employed to condense the amalgam must be coupled with athrust pressure that serves to provide a well adapted, in addition to aswell condensed, filling. Thus it has lbeen found that a continuoussqueezing pressure on the amalgam as it is carried to the tooth togetherwith a forceful insertion of the amalgam into the tooth provides afilling that will set well. The filling is well adapted in that it iillsthe cavity completely and provides a tight bond and in addition iscondensed at the point at which the amalgam is inserted into the tooth.

Accordingly, it is a further object of this invention to provide aninstrument which can continuously condense and feed amalgam under forceinto a tooth cavity, thereby employing the continuous feed principlewhich applicant has discovered. The advantage afforded by meeting thisobject is that one instrument and one procedure is necessary to carry,condense and adapt the amalgam.

It is a further object of this invention to provide a combinationamalgam condenser and carrier which, in its design, takes intoconsideration the very viscous nature of amalgam by avoiding anyappreciable discontinuities and sharp changes in direction of feeding orrate of gradual decrease in cross-sectional area while condensation andfeeding progresses.

It is a more specific object of this invention to provide a combinationdental amalgam carrier and condenser, whereby the position of theinstrument need not be changed to condense the amalgam in the cavityafter depositing the amalgam therein from the instrument.

Other objects include the ability of the instrument to be rapidlydisengaged for cleaning; complete disposability of the entire innerworking mechanism; an instrument which provides denser amalgam fillingswithout the an noying vibrations associated with conventional mechanicalcondensing instruments; and an instrument which provides fingertipcontrol of the amount and force of amalgam iiow.

' The objects of this invention are accomplished in one embodiment, byproviding a dental tool adapted to be attached to the conventional andcommonly used straight dental handpiece of a dental engine, therebyusing the dental engine as a source of rotational drive.

Other objects and purposes of this invention will become apparent from aconsideration of the following description taken in conjunction with thedrawings, in which:

FIG. 1 is a perspective view of an assembled embodiment of a dental toolmade according to this invention;

FIG. 2 is a longitudinal cross-sectional view of the FIG. l dental tool;

FIG. 3 is a cross-sectional along the plane 3 3 of FIG. 2 showing ameans for retaining the screw conveyor in the housing;

FIG. 4 is a cross-sectional view along the plane 4-4 of FIG. 2 showingthe relationship between the plunger and housing of the amalgamreservoir;

FIG. 5 is a perspective view of the output end of the screw conveyoremp-loyed showing a spring portion separated from the end of the taperedportion;

FIG. 6 is a perspective view similar to FIG. 5 showing the springportion attached to the end of the tapered portion of the amalgamconveyor; and

FIG. 7 is a cross-sectional view taken along the plane 7-7 of FIG. 6showing the connection between the spring and tapered screw portions ofthe amalgam conveyor.

The dental tool 10 shown in FIG. 1 has a housing 11 which includes atapered forward portion 11F and a cylindrical rearward portion 11R aswell as a reservoir portion 12. A finger operated plunger 14 is slidablymounted within the reservoir 12 so that the operator can control thefeed of amalgam through the tool 10. A hollow curved tube 16communicates to the forward end of the housing 11 so that amalgam whichis conveyed through the housing 11 will be conveyed through the tube 16to be ultimately applied to fill a cavity of a tooth.

The construction and operation of the dental tool 10 can be bestunderstood from the FIG. 2 longitudinal cross-section. The mostsignificant feature Iof this dental tool 10 is the amalgam conveyorcomposed of a tapered screw conveyor 18 with threads 18T having asubstantially constant pitch and a helical spring 20 attached to theforward end of the conveyor 18. The screw conveyor 18 is tted within thehousing 11 so that the conveyor 18 is free to rotate about its majoraxis. The threads 18T of the conveyor 18 are positioned flush againstthe innei wall of the housing 11 so that they will provide a wipingaction on the inner wall and convey all the amalgam in a forwarddirection as the screw conveyor 18 rotates.

The screw conveyor 18 tapers down toward its discharge end so that thereis a smooth and continuous transition from the threads 18T of the screwconveyor 18 to the helical spring 20. In this fashion, the spring 20forms a continuation of the threads 18T. The spring 20 is tted withinthe curved tube 16 so as to provide a wiping action on the inner wallsof the tube 16 in much the same fashion as do the threads 18T provide awiping action on the inner wall of the housing 11. The importance lofthis wiping action lies in the nature of the amalgam conveyed by thisdental tool 10. The housing 11 and tube 16 are normally made of`stainless steel to which amalgam tends not to stick. However, if thewalls of the stainless steel parts are not continuously wiped free ofamalgam, there will he a tendency for amalgam to ybuild up and harden.Once it does, the amalgam that is being conveyed will have a readytendency to stick to the hardened amalgam and thus provide a build up ofhardened amalgam that will cause jamming of the instrument. Furthermore,even if the build up does not become extensive enough to directly engagethe threads 18T, the hardened amalgam will ultimately break off in partsso as to provide chips that will jam the conveyor at its forward end.

The reasons why the wiping action between the threads 18T and the innerwall ,of the housing 11 as well as between the spring 20 and the innerwall of the curved tube 16 are important also dictate another importantstructural feature of the device of this invention. In general, it isimportant that there be no sharp discontinuities in the path of theamalgam. In particular, it is important that the effectivecross-setcional area through which the amalgam is being -forced decreaseat a continuous rate that avoids both sharp discontinuities and sharpchanges in the rate at which this elective cross-sectional areadecreases. This last feature is essential when handling a materialhaving the peculiar resistance to deformation properties that amalgamhas. A material as viscous as amalgam resists change of direction in afashion that makes it important to avoid sharp discontinuities in thepath of the amalgam. More particularly, because amalgam in generalresists all changes or deformations, it becomes essential to avoid notonly sharp discontinuities, ybut also sharp changes in the rate at whichthe amalgam is being squeezed and condensed.

Thus it would be possible for the conveyor 18 and associated housing 11to have a longitudinal profile which provides a varying rate of decreasein cross-sectional area through which the amalgam passes. It would evenbe possible for there to be no decrease in cross-sectional area overportions of the conveyor travel. However, there must be an avoidance ofany sharp changes in the magnitude of the rate at which this effectivecross-sectional area (through which the amalgam passes) decreases.

There are devices which have been proposed for the conveying andinjection of cement into tooth cavities and particularly into rootcanals. Two such devices are illustrated in German Patents 483,465 datedMarch 30, 1927 and 484,480 dated October 17, 1929, both issued to Mr.Eugen Weigle. Both of the devices illustrated in the Weigle patentsexhibit sharp breaks in the rate at which the cross-sectional area ofthe conveyor decreases. Thus whatever the value may be of the Weigledevices in conveying cement to a tooth, such devices would simply jam upif one attempted to feed amalgam through them.

It is further important that the conveyor 18 be designed in such afashion that there is a continuous positive feed of amalgam throughoutthe length of the conveyor. If any significant portion of the threads18T were omitted from the conveyor 18, the amalgam would tend tosolidify (that is set) in the area where the threads 18T were missingand thus cause the instrument to jam. It is important for the properoperation of any device embodying this invention that there be acontinuous positive feed or drive of amalgam through the conveyor fromreservoir to exit tip.

A rod 22 is connected to the screw conveyor 18 and extends out the backof the tool 10 to be coupled to a power source which rotates the rod 22,screw conveyor 18 and spring 20 assembly to provide an amalgam conveyor.Because the pressure of the amalgam on the screws of the screw conveyor18 will tend to force the screw conveyor 18 back, an anchor portion 24is attached to the rear of the screw conveyor 18 to permit the screwconveyor 18 to rotate but to prevent the screw conveyor 18 from movingin a longitudinal direction. When the 'screw 26 is screwed into place,its end extends into an annular groove 28 cut into the anchor 24. Theend of the screw 26 is not screwed down tight enough to bind on thegroove 28 but simply extends into the groove 28 to prevent longitudinalmovement of the screw conveyor 18. Thus the screw conveyor 18 is free torotate while being held against longitudinal movement. A considerationof FIG. 3 will further clarify the relationship between the screw 16 andanchor 24.

It is clear from an observation of FIG. 2 and an understandinfy of itsoperation that the screw conveyor 18` will carry amalgam 30 forward fromthe reservoir 12. What may not be as obvious from observation is thatthis screw conveyor 18 will also serve to condense the amalgam (that is,squeeze out the mercury) as the amalgam is carried along` In order toprovide this condensing operation, it is essential that the screwconveyor 18 bc tapered inwardly towards its forward end. What happens isthat there is a build-up of pressure on the amalgam that serves tocondense the amalgam in much the same sense as does the normal dentaloperation of tamping.

The appropriate build-up of pressure occurs because the pitch of thethreads 18T on the tapered screw conveyor 18 is substantially constantand the rotary speed at which the conveyor 18 is operated also remainssubstantially constant throughout the filling operation. Hence, as theamalgam is moved from the larger diameter end of the threaded conveyor18 along the helical groove between the thread crests, the decreasingdiameter of this helical groove as it approaches the spring 20 causesprogressive compression and resulting condensation of the amalgam. Thus,by the time the amalgam reaches the flexible spring 20 it issubstantially condensed. This condensing operation is one of the majoradvantages of this invention because it means that an operation whichmay take as long as fifteen (l5) minutes is reduced to fifteen seconds.

The fact that the dental amalgam will be condensed if it is continuouslyfed under progressive pressure as the amalgam proceeds toward the cavityis of major importance and has not hitherto been recognized.

As may be seen from FIGS. 2 and 4, the reservoir 12, within whichamalgam 30 is contained, has a plunger 14 with a longitudinal groove 32riding on a longitudinal ridge 34 within the reservoir 12. Thus theplunger 14 is free to move up and down within the reservoir 12 but isnot free to rotate so that it retains its rotational orientation andwill not contact or damage the threads 18T on the screw conveyor 18.

The curved tube 16 has a small outwardly extending flange 3S on its backend which sits flush against the front end of the housing 11 and is heldagainst the front end of the housing 11 by a coupling nut 38. The spring20 extends to the forward end of the curved tube 16 so as to assure thatamalgam 30 will be conveyed out of the tool 10, and will not set withinthe tool 10. As may be seen in FIG. 2, the amalgam is deposited in atooth 36 cavity at which point pressure may be applied by the tool 10 tofinish condensing the amalgam and so form the filling 38. The spring hasa diameter such that it touches the inner wall of the tube 16, therebymaking sure that amalgam does not set thereon.

T wo small apertures 17 are located at the forward end of the walls ofthe curved tube 16. These small apertures serve a two-fold purpose.First, they serve as overflow valves to prevent jamming in case the tube16 shoud become too packed with amalgam. Secondly, they serve as escapevalves for the mercury which is being condensed out of the amalgam.

Within recent years, a school of thought has grown in dentistry whichadvocates and practices the use of an amalgam somewhat drier than hadhitherto been employed. The amalgam classically applied to a cavity hada mercury content of 54% or 55%. The amalgam was then condensed by thedentist in his tamping action to produce a filling having about 50%mercury (there being a small amount of sludge on the top, after tamping,which is carried off by the dentist). It has been found preferable inthe employment of the amalgam conveyor 10 of this invention to put anamalgam into the reservoir 12 that has approximately a 51% or 52%mercury content. The conveyor then serves to squeeze out between two andthree percentage points of mercury resulting in a filling .havingbetween 48% and 49% mercury at the bottom and about 50% mercury at thetop. It shall be understood herein that the phrase condensed amalgamrefers to amalgam which has had the small percentage of mercury squeezedout that makes it suitable for use as a filling.

The mercury that is squeezed out during the condensing operation issqueezed toward the rear of the housing so that it becomes mixed in withthe rest of the amalgam. For this reason, it is always desirable, if notnecessary, to place a greater quantity of amalgam in the reservoir thanis needed for the filling since the last portion of amalgam ejected willbe excessively mushy.

In spite of the fact that a drier amalgam mix is initially employed, thespeed with which the filling of a cavity can be undertaken by use of thedevice of this invention makes it possible for a dentist to completemultiple fillings at a single time from a single loading of thereservoir.

The helical spring The spring 20 is detachable from the screw conveyor18 so that the spring 20 can be replaced whenever it breaks. The spring20 is connected to the screw conveyor 18 so that it will be forced torotate as the screw conveyor 18 rotates and so that the spring 20l willform part of a screw conveyor system for conveying the amalgam. Becausethe tube 16 is curved and thus the spring 20 is bent, the rotation ofthe spring 20 establishes stresses and strains in the spring 20 thatgive the spring 20 a limited life. In two embodiments (one employing astainless steel spring 20 having a 0.062 inch diameter and the otheremploying a stainless steel spring 20 having a 0.082 inch diameter), thespring had to be replaced approximately once every day or two or onceevery thirty average fillings. Thus it is not only important that thespring 20 be detachable from the screw conveyor 18 but also that entiretool 10 be easy to disassemble so that the spring 20l can be readilyreplaced.

As may best be seen in FIGS. 5 and 6, the helical spring 20 has aslightly larger diameter over its rearward few turns in order to provideas even and smooth a transition from the threads 18T of the screwconveyor 18 to the turns of the spring 20. A smooth and even transitionis desired in order to avoid those kinds of discontinuities rwhich mightresult in the amalgam setting. As may be seen in FIG. 7, the rearwardend 42 of the spring 20 is bent to pass into a small hole 40 in theforward tip of the screw conveyor 18. When assembled, the spring 20 isso constrained -by the walls of the housing that the spring end 42 willbe held in the hole 40. Yet on disassembling the tool, it becomes verysimple to remove and replace the spring 20.

Proper operation of the tool 10 of this invention requires someattention to the design of the spring 20. As has been pointed out, it ispreferable that the rearward few turns of the spring 20 gradually taperoutward so as to provide as continuous a path as possible for theamalgam. Furthermore, as has ybeen pointed out, the spring 20 isemployed in part to provide a hollow core within which the amalgam canbe carried without setting. A major purpose of the -decreasing taper onthe conveyor 18 is to provide increasing pressure on the amalgam as itis conveyed forward to the discharge end so that the amalgam will becondensed. However, by the time the amalgam is ready to be passed to thespring 20, it has become relatively dry and it is important that it notlbe further condensed so as to avoid binding. Indeed, in order to conveythe amalgam from the tip of the conveyor y18 forward, it is desirable,if not necessary, that the effective `cross-sectional area through whichit passes be increased somewhat as the -condensed amalgam leaves the tipof the conveyor 18 to assure that the amalgam will not bind before it isapplied to the tooth cavity. In the embodiment shown, the effectivecrosssectional area across the spring 20 is greater than the effectivecross-sectional area of the groove through which the amalgam passes atthe end of the conveyor 18.

To provide an adequate size hollow core, it has been found that helicalspring 20 diameters 'below 0.062 inch tend to cause a problem inadequately conveying the amalgam without creating such back-up pressureas to run the risk of setting. However, if the spring diameter is toolarge, the amalgam in the hollow core will not all be carried forwardand will, as a consequence, set within the dental tool 10. Spring 20diameters up to approximately 0.156 inch have been found useable anduseful. Spring 20 diameters larger than 0.156 inch create the problem ofhaving amalgam lodge at the core of the spring 20 and thus solidifythere.

For reasons similar to those that dictate certain minimum and maximumspring diameters, there are certain minimum and maximum wire diameterconsiderations which have to ybe taken into account. Too small a wirediameter will mean that the spring 20 will be too weak and will compressunder the pressures involved. Diameters down to 0.012 inch have beenfound useful and it is preferred 4down to 0.012 inch be the minimum wirediameter employed in the spring 20. Wire diameters that are too langehave the problem of providing a spring 20 which is too rigid as well astaking up too much space so that there isnt adequate area for theamalgam to pass through. The rigidity of the spring means that it willbreak too frequently. It is preferred to use a Iwire dia-meter nogreater than 0.025 inch for these reasons. A stainless steel spring 20having a wire diameter of 0.015 inch has been found optimum; having themaximum life consistent with the rigidity necessary to push the amalgamalong. Wire diameter is an important factor in spring 20 life.

The pitch of the spring 22 is another factor that must be taken intoconsideration and it is preferred to use a spring 20 design that has apitch somewhere between five turns to the inch and 32 turns to the inch.The amalgam is not properly carried along if the spring pitch is outsideof those limits. If fewer than five turns to the inch is employed, thereis insufficient longitudinal crust to the amalgam, and if more than 32turns to the inch is employed, most of the amalgam will be in the core fthe spring and very little will be between the thread so that aninadequate amount will be carried.

Accordingly, of all the elements of the dental tool 10 of thisinvention, the spring is the most critical and the one which has to bedesigned with the greatest care in order to get optimum performance.

For ease of use, it is very important that the front end of the amalgamconveyor .10 be curved and for that reason the curved tube 16 isprovided. This permits the dentist to hold the amalgam conveyorconveniently while applying the outlet end of the conveyor appropriatelyto the tooth. It shall be understood that it is within the presentinvention to accomplish this change in direction of ow of amalgam forthe convenience of the user by means of a tube 16 with a sharp angularbreak rather than a curved form. It would thus be possible to employsmall gears in order to connect the main screw conveyor 18 to a helicalspring at an an-'gle to the main screw conveyor 18 so as to provide acontinuous screw conveying of amalgam through the dental tool. Such isnot shown herein because this would be 'a more complex, more expensiveand generally less desirable embodiment for the invention even though itwould permit avoiding having to curve the spring 20 and thus couldresult in an amalgam conveyor tool where no part would have to bereplaced on a regular basis.

The above description of a tube 16 having a sharp angular break ratherthan a curved form should not be understood to detract from theimportance of the design feature, mentioned earlier, that sharpdiscontinuities and sharp changes in the rate at which the effectivecross-sectional area decreases must be avoided. A discontinuity in thetube 16, at a point where the amalgam is no longer being condensed, maybe tolerated only if the design is such that the cross-sectional area iskept substantially contant throughout the length of the tube 16. A sharpchange in cross-sectional area even in the tube 16 portion of theamalgam conveyor, is likely to cause setting of the amalgam and jammingof the conveyor.

The term amalgam is employed throughout the specification and claims torefer to the dental filling material employed because the silver-mercurymixture is the dominant filling material used in the art. However, itshall be understood that the term amalgam herein shall be considered tocover any dental filling material having ha. consistency such that itcould be fed Iby the device of thls invention.

This and other variations in the embodiment disclosed ywould be apparentto those in this art and the following claims shall be understood toencompass all such variations and modifications.

What is claimed is:

1. An amalgam condenser and carrier comprising in combination:

a housing having an inlet opening adjacent one end -and a dischargeopening at the opposite end of said housing;

at least the interior of said housing decreasing progressively indiameter from adjacent said inlet opening to said discharge opening, ascrew conveyor supported for rotation within the interior of saidhousing and complementary in shape thereto,

said conveyor having threads thereon of uniform pitch and depth, wherebythe groove dened by said threads comprises a spiral passage from saidamalgam, said passage being of uniform depth and progressivelydecreasing uniformly in diameter to said discharge opening of saidhousing and upon rotation of said screw in a feeding directionsimultaneously feeds and condenses said amalgam without sharp changes inmagnitude and direction to insure uninterrupted feeding movement of saidamalgam through said housing from said inlet to said discharge openandmeans to rotate said screw in said feeding direction.

2. The amalgam condenser and carrier according to claim 1 in which saidscrew conveyor is fitted relative to the inner wall of said housing soas to provide a wiping action between the tips of the threads of saidscrew conveyor and the inner wall of said housing.

3. The amalgam condenser and carrier according to claim 1 includingpositioning means operable relative to said screw conveyor to preventany appreciable axial movement thereof relative to said housing.

4. The amalgam condenser and carrier according to claim 1 furtherincluding an amalgam reservoir communicating with said inlet opening.

5. The amalgam condenser and carrier according to claim 4 furtherincluding a plunger in said reservoir operable to be pressed toward saidinlet opening of said housing to insure the delivery of amalgam fromsaid reservoir to said spiral passage between said threads on said screwconveyor.

6. The amalgam condenser and carrier according to claim 1 furtherincluding a curved tubular discharge tube connected to the discharge endof said housing and further including a flexible helical springrotatably driven within said curved tubular discharge tube by said screwconveyor to insure discharge of condensed amalgam from said curvedtubular tube.

7. The amalgam condenser and carrier according to claim 6 in which theouter diameter of said spring is substantially equal to the innerdiameter of said curved tubular discharge tube, whereby said springwipingly engages the inner walls of said curved tubular tube.

8. The amalgam condenser and carrier according to claim 7 in which therearward end of said spring terminates in a hook, said hook being asegment of the diameter of said spring and disposed in a hole in thesmaller end of said screw conveyor to connect the spring thereto forrotation therewith.

9. The amalgam condenser and carrier according to claim 8 in which thediameter of the wire constituting said helical spring is between 0.012inch and 0.025 inch.

inch.

9 10 10. The amalgam condenser 'and carrier according to FOREIGN PATENTSclaim 8 in which the diameter yof said forward portion of 483,465 3/1927Germany said spring is substantially between 0.062 inch and 0.156484,480 10/1928 Germans/ References Cited 5 OTHER REFERENCES UNITEDSTATES PATENTS German lprinted application #1112810, 8/ 1961, Lentulo 3260 Ldige, 32-27, 4 pages spec, 2 pages drawing.

Heine 222-413 Benson 222 413 10 R. PESHOCK, Assistant Exammer.

